Why do I need a passphrase and a pin?

Your passphrase is the unique key that can open your HD wallet anywhere, on any device. 12 words are easy to copy and paste, but it'd take a while to type on a mobile device. We don't want to ask you to type it every time you make a purchase with us. Therefore, we ask you to set a 4-digit PIN.

We understand that 4-digit PIN is easy to brute-force, so we don't use your PIN to encrypt your master key directly. Instead, your PIN is sent to our server in exchange for a long token, which is used to decrypt your encrypted master key stored locally in your browser. If the PIN is entered incorrectly five times, the long token on the server is erased, which renders the locally encrypted version of the master key useless. The only way to access your wallet then will be using your 12-word passphrase.